Lantibiotics are bacterially-produced antimicrobial peptides that possess unique chemical and biological properties owing to their containing a variety of unusual amino acid residues. Lantibiotics are defined as such by the presence of lanthionine or β-methyllanthionine, which are introduced by a posttranslational process in which serine or threonine is dehydrated to the corresponding dehydro residue, which then reacts in a Michael-type addition of a cysteine sulfhydryl group to the double bond of the dehydro residue to form a thioether link. Mature antibiotics typically contain one or more dehydro residues that do not participate in lanthionine bridges. The unique properties that are conferred by these unusual residues results in their being useful components in the design of novel biomolecules.
Nisin is a lantibiotic that is effective against a wide range of gram-positive bacteria. Nisin is a small peptide that is produced by Lactococcus lactis, a small bacterium that naturally occurs in milk, and nisin is most stable in acidic conditions. Nisin is also soluble in aqueous environments, but it may be stored at ambient temperatures.
Sublancin, another peptide, is a natural product produced by B. subtilis 168. Additionally, sublancin has structural features and physical properties, such as the presence of disulfide bridges and extraordinary stability, that are unprecedented among the known lantibiotics. Sublancin has also proven suitable for the treatment of a bacterial infection. In addition, a bacterial-growth-inhibiting effective amount of sublancin of the invention may be added to a food for preservation against bacteria-mediated spoilage of the food. See U.S. patent application Ser. No. 09/462,478.
Previous methods of inhibiting bacterial outbreaks typically used these lantibiotics separately and their usefulness was limited because the lantibiotics, when used separately, were not effective until after the germination of the spore.
PCT Application WO 99/03352 discloses that a composition comprising a combination of sublancin and nisin would be suitable for killing or inhibiting growth of bacteria (see page 3, lines 8-12, and page 10, lines 4-8). However, there is no disclosure or suggestion regarding the use of the combination for preventing or inhibiting the germination of spores.
Prior art sterilization methods for preventing or inhibiting the germination of spores (such as those using hypochlorite and chlorine dioxide) involve the use of dangerous toxins that require evacuation and quarantine during treatment, and are not at all suitable for use in or around people, animals or food.
Therefore, an improvement is needed over the previous methods that can be used safely both outdoors and indoors, and in and around people, animals and food, without necessitating any evacuation or quarantine during application.